Friday, February 10, 2012

Inter-Plant Communication

Color shows a change in biological activity in plants on the right, caused by a gas emitted by cut plant on the left.
I wrote in an earlier post about a TED lecture, The Roots of Plant Intelligence. Now an experiment at the University of Essex in the UK has shown visually, for the first time, how when one plant is cut (mimicking attack by a herbivore), it emits a gas that causes nearby plants to alter their chemistry to be less appealing to herbivores.

To see this effect in a magical-looking (but scientific) way, take a look at this short BBC video.

(The image above is from the video, and I took it from the BBC website. Thanks to Las Pilitas Nursery for sharing this BBC video on FaceBook, sending me off on this tangent!)

People have also demonstrated this effect using California sagebrush cuttings. I read about this experiment, done at the University of California at Davis in 2009, in this Science Daily article  These scientists also established that herbivores did indeed react to the changes in the neighboring plants (and not directly to the gas given off): "Choice and no-choice experiments indicated that herbivores responded to changes in plant characteristics and were not being repelled directly by airborne cues released by clipped individuals."

They also found that " Plants with root contact between neighbors, but not air contact, failed to show this response." - I wondered why not?

And I found the answer in this abstract of a scholarly article, Plant-to-Plant Communication Mediating In-Flight Orientation of Aphidius ervi, in the Journal of Chemical Ecology. These folk found that when a broad bean is infested with aphids, it changes its chemistry to attract a specific aphid parasite, A. ervi. - This in itself is amazing. Also -- the plants'  non-infested parts send out a volatile chemical signal that stimulates nearby bean plants to produce the same attractant. Wow!

And about the root contact: They also found out that "This change was not observed when root contact was prevented among plants that had their aerial parts in close proximity, suggesting that an exudate from the roots of the infested plant may cause the induction of the attractive volatiles in uninfested plants." And they confirmed this by another experiment - So that's why. The plants switch to another type of signal via the roots if that is available -- aren't plants amazing!


BTW, I'm sorry not to list the actual scientists responsible in each case - But that's science for you. It's all about the results, not who got them! You can see all the worthy pioneers' names if you click the links.

2 comments:

The Sage Butterfly said...

This is so interesting. I have long believed that plants are way more intelligent than we ever realized. I hope we continue to discover more about the intelligence of plants.

Country Mouse said...

Thanks for your comment - There is a surprising amount of research going on into the "neurology" of plants and all this kind of thing. It blends into the - well regions I can't follow. I watched a video of a nice gentle seeming guy called the plant whisperer talking on this topic and saying if we get the intuition that say a plantain doesn't want us to pick it we shouldn't because it might alter itself chemically to be not so good for us. I'm thinkin' - when is a plantain going to lay down its life for us, ever? And I don't know if we can get intuitions from plants. It's a nice idea and I like to imagine around it but I don't know if it's possible. But I do have my moments.